Among the cities hit in the volleys of strikes on Monday was Dnipro, a central Ukrainian city that had been seen as a relatively safe haven for internally displaced people fleeing front-line areas in the ground war in the southeast.

“A massive rocket attack,” Valentyn Reznichenko, the head of the regional military administration, wrote on Telegram. “There are dead and wounded.”

Residents heard about a dozen explosions early Monday morning. Alina Holovko, the head of a nongovernmental organization assisting people displaced by the war, said the attack had shattered any sense of safety in the city.

“I am now scared to bring people here,” Holovko said in a telephone interview.

“After today, we are thinking of evacuating again people we already evacuated. But where to? Western Ukraine? It’s scary there, too.”

Holovko said rockets struck apartment buildings and a bus stop.

“I cannot fit it in my head,” she said. “We don’t know how many victims there are.”